As the stricken Carnival Triumph is towed back to port in Mobile, Ala., the 3,143 passengers and 1,086 crew members stranded aboard are understandably restless. They’ve been stuck on board the ship since Sunday morning, when a fire in the ship’s engine room knocked out its propulsion system, leaving it stranded in the Gulf of Mexico.

Reports of the passengers’ ordeal over the ensuing four days have been harrowing. According to text messages sent to relatives and interviews with people on board, the smell of rotting food abounds. Toilets are backed up, forcing many to use red biohazard bags to go to the bathroom. With the air-conditioning system offline, the staterooms are too hot to sleep in, and some passengers have reportedly moved their mattresses to the deck. According to a statement released by Carnival, only one dining room has reliable power for serving hot coffee and, sporadically, hot food.

But possibly the worst part about the past week for the passengers of the Carnival Triumph is that there’s been no escape. So far, only two passengers have been moved off the ship: Rachel Alderete, 54, who was in desperate need of emergency kidney dialysis, was transported to the Triumph’s sister ship, the Carnival Legend, on Tuesday to be taken to Texas for treatment. The following day, a second passenger was taken off the ship because of a pre-existing medical condition, Carnival spokeswoman Joyce Oliva tells TIME. Both were moved to other Carnival ships that had diverted their courses in order to assist with the rescue mission.

However, these emergency measures underscore a question on the minds of many observers: Why not take all the passengers off the stricken Carnival Triumph?

It turns out that it’s not that simple. Just moving a single passenger is a delicate dance, according to Lieutenant Lily Zepeda, public-affairs officer for the U.S. Coast Guard District 8, which is coordinating the response to the cruise-ship crisis from its New Orleans–based office. The Coast Guard cutter Vigorous, a 210-ft. (64 m) vessel that was called on to escort the cruise ship just hours after it was disabled, launched a small boat to courier Alderete from the Triumph to the Legend. “Our small boat would come alongside one of the cruise ships, take the passenger and then go alongside the other cruise ship and drop the passenger off,” Zepeda explains to TIME.

The whole process can take 15 minutes to an hour for just one person, making it an understandably arduous task to move all 4,200 people on board. (One passenger wasn’t even able to make the trip: according to the New York Times, Alderete’s sister was supposed to accompany her, but choppy waters prevented her departure.) And that’s assuming everyone is capable of the move. Among the passengers are likely many “that are really young, really old. We don’t know the physical fitness of everyone,” says Zepeda. All told, offloading the passengers with the help of the Vigorous could have taken longer than towing the ship back to shore.

Still, it couldn’t have been easy for the passengers on board the Triumph to watch as three working Carnival cruise liners stopped by to drop off hot prepared meals and nonperishable food. Unfortunately, none of the ships in the area had enough cabins to take on the Triumph’s 3,143 guests. “If it wasn’t a life-threatening medical emergency, we probably wouldn’t have gotten involved” in transferring passengers in the first place, Zepeda says.

Despite the discomfort of the Triumph’s five-day saga — by the end of which the ship’s sewage system had backed up and breakfast menus occasionally consisted of cold waffles and candy, according to the New York Times — conditions never got dire enough to prompt an evacuation. Lifeboats are deployed only in the case of emergency, and both Carnival and the Coast Guard agree that this situation didn’t fit the bill. “We evaluated a wide range of options, but the safest and most expedient solution was towing the ship back to port,” says Oliva. And despite its shortcomings, the Triumph “is still a stable and safe platform,” according to Zepeda. “Unfortunately, despite the discomfort, it’s probably the safest place for them to be, rather than trying to transfer them back and forth via another method.”

Three tugboats have been slowly pulling the cruise ship back to port — a mission that ended up taking five days and was hampered Thursday afternoon just miles offshore by a broken tow line. For the passengers on board the Carnival Triumph, the end of the voyage can’t come soon enough.